Detailed observations of NGC 4151 with IUE - I Low dispersion data up to 1979 January*

This paper reports low resolution ultraviolet spectroscopic monitoring of NGC 4151 with IUE in the period 1978 February to 1979 January. Observations were made at seven different epochs. Continuum points can be isolated in both longwave (1950–3250 Å) and, with some difficulty, shortwave (1150–1950 Å) regions. The observed continuum shows a long wavelength $$f_\nu\propto\nu^{-2}$$ component and a flatter short wavelength component. There is some evidence that these do not vary exactly together. A value for E(B–V) between 0.05 and 0.10 mag is derived from the weakness of the interstellar λ 2200 Å feature.